Our planet is around 4.54 billion years old – and as you might expect, it has changed a lot in that time.

After all, we humans change almost unrecognisably in a 70(ish) year life span; imagine how much you’d change if you have over four billion years to do so.

So it goes without saying that the continents we see on our map now are very different to those that our distant ancestors knew, and they’re almost unrecognisable from those that came long, long before us.

But according to a new paper, recently published in the journal Nature, our planet might have changed more significantly than we ever before knew.

That’s as a result of new research into zircons, which are the oldest minerals here on Earth, which proves that subduction – the process by which tectonic plates shift by pushing under one another, thus forming ocean trenches, volcanoes, and causing earthquakes – has been happening on our planet’s surface for much longer than we knew.

In fact, the chemical signatures that the researchers discovered in the zircons prove that subduction was happening over four bullion years ago – so even that long ago, our plates were busy shaping our land masses into something resembling the ones we know now.

Incredibly, this can be understood from zircons that are as small as a grain of sand, since their crystallisation process locks in up to 500 million years of history – and, as Professor John Valley explains in a statement, the zircons they studied prove something quite significant:

“They’re tiny time capsules and they carry an enormous amount of information. What we found in the Jack Hills is that most of our zircons don’t look like they came from the mantle, they look like continental crust. They look like they formed above a subduction zone.”

By understanding that subduction was present all that time ago, the scientists were able to disprove the theory that at one time, Earth was covered by one continuous unbroken crust, known as a ‘uniform stagnant lid’.

And understanding this helps researchers to begin to comprehend the processes by which our planet and its complex terrains were formed, and when features like mountain ranges began to emerge.

Though all the questions aren’t answered yet, one thing that is incredible is our planet’s ability to preserve its history in mere grains – as well as humankind’s growing ability to interpret and learn from that hidden data.

Who knew so much could be hidden in one grain?

If you thought that was interesting, you might like to read a story that reveals Earth’s priciest precious metal isn’t gold or platinum and costs over $10,000 an ounce!